use bevy::prelude::*;
use std::fs::File;
use std::io::{BufRead, BufReader};

fn main() {
    App::build()
        .add_resource(WindowDescriptor {
            title: "Advent of Code".to_string(),
            width: 1920,
            height: 1080,
            ..Default::default()
        })
        .add_resource(ClearColor(Color::rgb(0., 0., 0.)))
        .add_startup_system(setup_camera.system())
        .add_startup_system(read_input_file.system())
        .add_stage("mark")
        .add_system_to_stage("mark", mark_sum_pair.system())
        .add_system_to_stage("mark", mark_sum_triple.system())
        .add_stage("report")
        .add_system_to_stage("report", print_product_pair.system())
        .add_system_to_stage("report", print_product_triple.system())
        //.add_plugins(DefaultPlugins)
        .run();
}

fn setup_camera(mut commands: Commands) {
    commands.spawn(Camera2dComponents::default());
}

struct Expense(i32);
struct FlaggedPair;
struct FlaggedTriple;

fn read_input_file(mut commands: Commands) {
    let f = File::open("./inputs/day_1.txt").unwrap(); // TODO: Error handling on systems?
    for line in BufReader::new(f).lines() {
        let expense = line.unwrap().trim().parse().unwrap();
        commands.spawn((Expense(expense),));
    }
}

fn mark_sum_pair(mut commands: Commands, expenses: Query<(Entity, &Expense)>) {
    for (entity_1, expense_1) in expenses.iter() {
        for (entity_2, expense_2) in expenses.iter() {
            if expense_1.0 + expense_2.0 == 2020 {
                commands.insert_one(entity_1, FlaggedPair);
                commands.insert_one(entity_2, FlaggedPair);
            }
        }
    }
}

fn mark_sum_triple(mut commands: Commands, expenses: Query<(Entity, &Expense)>) {
    for (entity_1, expense_1) in expenses.iter() {
        for (entity_2, expense_2) in expenses.iter() {
            for (entity_3, expense_3) in expenses.iter() {
                if expense_1.0 + expense_2.0 + expense_3.0 == 2020 {
                    commands.insert_one(entity_1, FlaggedTriple);
                    commands.insert_one(entity_2, FlaggedTriple);
                    commands.insert_one(entity_3, FlaggedTriple);
                }
            }
        }
    }
}

fn print_product_pair(flagged_expenses: Query<With<FlaggedPair, &Expense>>) {
    let mut product = 1;
    for expense in flagged_expenses.iter() {
        product *= expense.0;
    }
    // TODO: Put it on the screen!
    println!("Product Pair: {}", product);
}

fn print_product_triple(flagged_expenses: Query<With<FlaggedTriple, &Expense>>) {
    let mut product = 1;
    for expense in flagged_expenses.iter() {
        product *= expense.0;
    }
    // TODO: Put it on the screen!
    println!("Product Triple: {}", product);
}